This indicates detection of HTTP requests with suspicious URI.
Without sufficient sanitizing of user-supplied inputs to a web-server, this could potentially lead to various issues such as exposing buffer overflow vulnerabilities and remote code execution. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application.
Any unprotected HTTP server is vulnerable
System Compromise: Remote attackers can gain control of vulnerable systems.
Monitor the traffic from that network for any suspicious activity.